Tokkai Hei 6-10787 published by the Japanese Patent Office in 1994 discloses a technique wherein main fuel and auxiliary fuel are injected by one nozzle to supply two kinds of fuel to an internal combustion engine for vehicles of a compression self-ignition type. This nozzle is filled with the auxiliary fuel at the tip, and injects the auxiliary fuel prior to a main fuel injection.
Tokkai Hei 6-307307 published by the Japanese Patent Office in 1994 discloses control of the injection proportion of two kinds of fuel. Alcohol is used for the main fuel, a diesel fuel is used for the auxiliary fuel, and the supply proportion of the main fuel and the auxiliary fuel is controlled by varying the amount of auxiliary fuel which fills the tip of the nozzle.
This aims to improve the ignition characteristics of an engine which uses alcohol as a main fuel.
That is, by first injecting the diesel fuel which has better ignition characteristics than alcohol, the diesel fuel undergoes compression ignition first, and the flame then spreads to the alcohol, the main fuel.
Also in a gasoline engine which changes over between compression self-ignition combustion and spark ignition combustion according to running conditions, the air-fuel ratio region in which self-ignition combustion is possible can be expanded by using two kinds of fuels in this way.
Compression self-ignition combustion is effective in largely reducing fuel consumption to enable combustion with a very lean air-fuel ratio. However, combustion stability tends to decline under such a lean air-fuel ratio, while on the other hand at a rich air-fuel ratio, knocking easily occurs. Therefore, if high octane fuel which is effective in preventing knocking is used to allow self-ignition combustion more easily, while low octane fuel which has high combustion stability is used at a lean air-fuel ratio, the self-ignition combustion region can be enlarged.
However, having two kinds of fuel tanks for this purpose increases the manufacturing cost of a vehicle. Further, as which of these fuels is used the most depends on running conditions, it is difficult to use up both of the fuels simultaneously, and the frequency of refuelling also increases as a result.
It is therefore an object of this invention to enable supply of plural fuels to an engine without increasing the frequency of refuelling.
In order to achieve the above object, this invention provides an apparatus for supplying fuel in a fuel tank to an internal combustion engine, comprising a separating device which separates fuel in the fuel tank into plural fuel components, a sensor which detects a running condition of the engine, and a mechanism which supplies the plural fuel components to the engine in different proportions depending on the running condition.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.